I was the Exec Producer of a commercially recorded jazz album (Richard Todd - With A Twist) and I have a recording studio in my home. As a result, I've spent enough time with this question to weigh in.
I can tell you from experience that many uses of the term are a stretch. If there's an obvious (and repeated across multiple source materials) FR deviation in (for example) a loudspeaker connected to neutral (preferably SS) electronics, that certainly justifies the tag. However, many people cite subtle timbral deviations which may be attributable to the recording or even the eccentricities of the instrument being recorded.
The phenomenon is real, but overused IMO.
I can tell you from experience that many uses of the term are a stretch. If there's an obvious (and repeated across multiple source materials) FR deviation in (for example) a loudspeaker connected to neutral (preferably SS) electronics, that certainly justifies the tag. However, many people cite subtle timbral deviations which may be attributable to the recording or even the eccentricities of the instrument being recorded.
The phenomenon is real, but overused IMO.